Quantitative analysis of myelin protein gene expression during development in the rat sciatic nerve

We determined the temporal profile of expression of the genes encoding the P0 glycoprotein, the myelin-associated glycoprotein (MAG), the myelin basic protein (MBP), the proteolipid protein (PLP), and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in the sciatic nerve of rats. The level of expression of the MAG gene occurred maximally in animals 13 days of age, approximately one week earlier than the peak expression of the MBP and P0 genes. The genes encoding PLP and CNP were not expressed developmentally in a manner that correlated with the myelination of the sciatic nerve. Furthermore, using RNA synthesized in vitro, specific for each of the myelin protein genes, we have determined the absolute amounts of messenger RNA for the various myelin proteins in total RNA from sciatic nerves. P0 and MBP RNA were present at very high levels, whereas the amount of MAG, PLP and CNP RNA were much less.

Identification of cellular proteins binding to the scrapie prion protein

The scrapie prion protein (PrPSc) is an abnormal isoform of the cellular protein PrPc. PrPSc is found only in animals with scrapie or other prion diseases. The invariable association of PrPSc with infectivity suggests that PrPSc is a component of the infectious particle. In this study, we report the identification of two proteins from hamster brain of 45 and 110 kDa (denoted PrP ligands Pli 45 and Pli 110) which were able to bind to PrP 27-30, the protease-resistant core of PrPSc on ligand blots. Pli 45 and Pli 110 also bound PrPC. Both Pli's had isoelectric points of approximately 5. The dissociation rate constant of the Pli 45/PrP 27-30 complex was 3 x 10(-6) s-1. Amino acid and protein sequence analyses were performed on purified Pli 45. Both the composition and the sequence were almost identical with those predicted for mouse glial fibrillary acidic protein (GFAP). Furthermore, antibodies to Pli 45 reacted with recombinant GFAP. The identification of proteins which interact with the PrP isoforms in normal and diseased brain may provide new insights into the function of PrPC and into the molecular mechanisms underlying prion diseases.

Differential release of cellular and scrapie prion proteins from cellular membranes by phosphatidylinositol-specific phospholipase C

The abnormal isoform of the scrapie prion protein PrPSc is both a host-derived protein and a component of the infectious agent causing scrapie. PrPSc and the normal cellular isoform PrPC have different physical properties that apparently arise from a posttranslational event. Both PrP isoforms are covalently modified at the carboxy terminus by a glycoinositol phospholipid. Using preparations of dissociated cells derived from normal and scrapie-infected hamster brain tissue, we find that the majority of PrPC is released from membranes by phosphatidylinositol-specific phospholipase C (PIPLC), while PrPSc is resistant to release. In contrast, purified denatured PrP 27-30 (which is formed from PrPSc during purification by proteolysis of the amino terminus) is completely cleaved by PIPLC. Incubation of the cell preparations with proteinase K cleaves PrPSc to form PrP 27-30, demonstrating that PrPSc is accessible to added enzymes. We have also developed a protocol involving biotinylation that gives a quantitative estimate of the fraction of a protein exposed to the cell exterior. Using this strategy, we find that a large portion of PrPSc in the cell preparations reacts with a membrane-impermeant biotinylation reagent. Whether alternative membrane anchoring of PrPSc, inaccessibility of the glycoinositol phospholipid anchor to PIPLC, or binding to another cellular component is responsible for the differential release of prion proteins from cells remains to be determined.

Scrapie and cellular prion proteins differ in their kinetics of synthesis and topology in cultured cells

Both the cellular and scrapie isoforms of the prion protein (PrP) designated PrPc and PrPSc are encoded by a single-copy chromosomal gene and appear to be translated from the same 2.1-kb mRNA. PrPC can be distinguished from PrPSc by limited proteolysis under conditions where PrPC is hydrolyzed and PrPSc is resistant. We report here that PrPC can be released from the surface of both normal-control and scrapie-infected murine neuroblastoma (N2a) cells by phosphatidylinositol-specific phospholipase C (PIPLC) digestion and it can be selectively labeled with sulfo-NHS-biotin, a membrane impermeant reagent. In contrast, PrPSc was neither released by PIPLC nor labeled with sulfo-NHS-biotin. Pulse-chase experiments showed that [35S]methionine was incorporated almost immediately into PrPC while incorporation into PrPSc molecules was observed only during the chase period. While PrPC is synthesized and degraded relatively rapidly (t1/2 approximately 5 h), PrPSc is synthesized slowly (t1/2 approximately 15 h) and appears to accumulate. These results are consistent with several observations previously made on rodent brains where PrP mRNA and PrPC levels did not change throughout the course of scrapie infection, yet PrPSc accumulated to levels exceeding that of PrPC. Our kinetic studies demonstrate that PrPSc is derived from a protease-sensitive precursor and that the acquisition of proteinase K resistance results from a posttranslational event. Whether or not prolonged incubation periods, which are a cardinal feature of prion diseases, reflect the slow synthesis of PrPSc remains to be established.

[Cricopharyngeal myotomy for upper esophageal achalasia]

Cricopharyngeal achalasia (CA) causes inability to swallow liquids or solids without initiating a violent coughing spasm. Etiological factors which may precipitate obstruction by cricopharyngeal spasm include neuromuscular disorders, radical oral surgery, central nervous system disease, and idiopathic disorders. Cricopharyngeal myotomy is a simple procedure which gives considerable improvement in swallowing. 2 cases with complete dysphagia who were able to swallow fluids and solids after excision of the cricopharyngeal sphincter are described.

Recurrent bilateral peripheral facial palsy

Facial nerve paralysis is a common otolaryngological diagnosis. Recurrent unilateral peripheral facial palsy is found in about 7 per cent of the cases. Simultaneous bilateral facial palsy is relatively uncommon and occurs in 0.3-2.0 per cent of cases of facial palsy. Recurrent, simultaneous, bilateral, idiopathic facial palsy to the best of our knowledge has never been reported. A case of recurrent, simultaneous, bilateral, idiopathic facial palsy is presented. No evidence of systemic or local disease was found in both attacks of peripheral facial palsies. The association with states of stress is the only common finding between the two attacks.

Acute upper airway obstruction due to myxoedema and upper airway abnormalities

Acute upper airway obstruction (U.A.O.) in adults is not as common as in children. The most common cause is choking on food, and associated endocrine disorders are among the rarest causes. Airway obstruction in adults has a variety of symptom-complexes, which manifest themselves as acute or chronic (incomplete) conditions, or only during sleep (sleep apnoea syndrome). There is an overlap between these symptoms and their aetiologies. A case of acute U.A.O. at the pharyngeal level in a hypothyroid patient is presented. Following airway relief and supplemental thyroxin treatment, the patient became asymptomatic during the daytime, but showed a severe form of sleep apnoea syndrome which required further surgical treatment to reach full cure.

Maqua (therapeutic burn) as an indicator of underlying disease

The origin and nature of the maqua (the Arabic therapeutic burn) is presented together with our clinical experience of patients previously treated by this traditional method. Maquas are small deep burns inflicted in areas either in proximity to a diseased organ or in points related traditionally to the original basic problem. These relationships may be rooted in historical ties between old Arab medicine and traditional Oriental, antique Egyptian, and Greco-Roman medicines. Maquas alone only rarely present a threat to the patient, but in many cases they may serve as an indicator of the original underlying disease. This and other folklore treatment modalities, together with the healers themselves, should be acknowledged by us, as markers for health problems or maybe for potential healing methods and doctor-patient relationships.

A thermodynamic analysis of monovalent cation permeation through a K(+)-selective ion channel

Ionic selectivity characteristics of the K+ channel from the sarcoplasmic reticulum were studied as a function of temperature in order to decompose the profile of Gibbs free energy along the conduction pore into its enthalpic and entropic components. For Li+, Na+, K+, and Rb+, the enthalpy of binding to the channel is close to zero. Activation enthalpies for transferring ions from bulk aqueous solution to the channel's selectivity region are 20-25 kJ/mol for Na+, K+, and Rb+ and substantially higher for Li+ and Cs+. Transfer of Li+ and Na+ to the selectivity region involved large favorable entropies. The results argue that the group IA cations shed about half their waters of hydration in permeating the selectivity region of this channel.

Omiderm: a synthetic cover for exposed areas in epidermolysis bullosa

Omiderm, a synthetic temporary skin substitute, was used for the treatment of skin defects in a newborn who suffered from epidermolysis bullosa. Omiderm served as a biological barrier, and its transparency allowed close observation of the wound healing process and early detection of local infections when they occurred.

Reactions of the sarcoplasmic reticulum calcium adenosinetriphosphatase with adenosine 5'-triphosphate and Ca2+ that are not satisfactorily described by an E1-E2 model

Phosphorylation of the sarcoplasmic reticulum calcium ATPase, E, is first order with kb = 70 +/- 7 s-1 after free enzyme was mixed with saturating ATP and 50 microM Ca2+; this is one-third the rate constant of 220 s-1 for phosphorylation of enzyme preincubated with calcium, cE.Ca2, after being mixed with ATP under the same conditions (pH 7.0, Ca2+-loaded vesicles, 100 mM KCl, 5 mM Mg2+, 25 degrees C). Phosphorylation of E with ATP and Ca2+ in the presence of 0.25 mM ADP gives approximately 50% E approximately P.Ca2 with kobsd = 77 s-1, not the sum of the forward and reverse rate constants, kobsd = kf + kr = 140 s-1, that is expected for approach to equilibrium if phosphorylation were rate limiting. These results show that (1) kb represents a slow conformational change, rather than phosphoryl transfer, and (2) different pathways are followed for the phosphorylation of E and of cE.Ca2. The absence of a lag for phosphorylation of E with saturating ATP and Ca2+ indicates that all other steps, including the binding of Ca2+ ions and phosphoryl transfer, have rate constants of greater than 500 s-1. Chase experiments with unlabeled ATP or with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) show that the rate constants for dissociation of [gamma-32P]ATP and Ca2+ are comparable to kb. Dissociation of ATP occurs at 47 s-1 from E.ATP.Ca2+ and at 24 s-1 from E.ATP. Approximately 20% phosphorylation occurs following an EGTA chase 4.5 ms after the addition of 300 microM ATP and 50 microM Ca2+ to enzyme. This shows that Ca2+ binds rapidly to the free enzyme, from outside the vesicle, before the conformational change (kb). The fraction of Ca2+-free E.[gamma-32P]ATP that is trapped to give labeled phosphoenzyme after the addition of Ca2+ and a chase of unlabeled ATP is half-maximal at 6.8 microM Ca2+, with a Hill slope of n = 1.8. The calculated dissociation constant for Ca2+ from E.ATP.Ca2 is approximately 2.2 X 10(-10) M2 (K0.5 = 15 microM). The rate constant for the slow phase of the biphasic reaction of E approximately P.Ca2 with 1.1 mM ADP increases 2.5-fold when [Ca2+] is decreased from 50 microM to 10 nM, with half-maximal increase at 1.7 microM Ca2+. This shows that Ca2+ is dissociating from a different species, aE.ATP.Ca2, that is active for catalysis of phosphoryl transfer, has a high affinity for Ca2+, and dissociates Ca2+ with k less than or equal to 45 s-1.(ABSTRACT TRUNCATED AT 400 WORDS)

Scrapie prion protein contains a phosphatidylinositol glycolipid

The scrapie (PrPSc) and cellular (PrPC) prion proteins are encoded by the same gene, and their different properties are thought to arise from posttranslational modifications. We have found a phosphatidylinositol glycolipid on both PrPC and PrP 27-30 (derived from PrPSc by limited proteolysis at the amino terminus). Ethanolamine, myo-inositol, phosphate, and stearic acid were identified as glycolipid components of gel-purified PrP 27-30. PrP 27-30 contains 2.8 moles of ethanolamine per mole. Incubation of PrP 27-30 with a bacterial phosphatidylinositol-specific phospholipase C (PIPLC) releases covalently bound stearic acid, and allows PrP 27-30 to react with antiserum specific for the PIPLC-digested glycolipid linked to the carboxyl terminus of the trypanosomal variant surface glycoprotein. PIPLC catalyzes the release of PrPC from cultured mammalian cells into the medium. These observations indicate that PrPC is anchored to the cell surface by the glycolipid.

Adenosine 5'-triphosphate at the active site accelerates binding of calcium to calcium adenosinetriphosphatase

The complex of Mg X ATP and the calcium adenosinetriphosphatase of sarcoplasmic reticulum (E X ATP) reacts with 50-300 microM Ca2+ to form phosphoenzyme (E-P X Ca2) with a rate constant of 70 s-1 (pH 7.0, 100 mM KCl, 5 mM MgSO4, 25 degrees C, and SR vesicles passively loaded with Ca2+). This rate constant is independent of Ca2+ concentration above 50 microM. It is 4-6 times faster than the rate constants of 11-15 s-1 for the conformational change associated with Ca2+ binding in the absence of activation by ATP. The reaction of 200 microM Ca2+ with enzyme preincubated in 0.9 microM [gamma-32P]ATP X Mg shows a burst of [32P]E-P X Ca2 formation. This result indicates that Mg X ATP bound to the active site, and not a regulatory site, can accelerate the conformational change associated with Ca2+ binding because this concentration of Mg X ATP is well below the Kd of 160-500 microM for the putative regulatory site. When an unlabeled ATP chase is added with the Ca2+ to enzyme preincubated with [gamma-32P]ATP X Mg, the amount of [32P]E-P X Ca2 that is formed increases with the concentration of ATP in the preincubation solution and is consistent with a maximum fraction trapped of 0.55 and Kd = 4.5 microM for the dissociation of Mg X ATP from the active site. The fact that labeled E X ATP can be trapped by added Ca2+ confirms the conclusion that dissociation of ATP from E X ATP X Ca2 is slow relative to phosphorylation.

[Determination of carcinoembryonal antigens in the blood of bullous and genetically determined skin diseases]

It was reported that increased levels of carcinoembryonic antigen (CEA) in blood were observed in patients with epidermolysis bullosa. We tested a group of total 82 patients with bullous dermatoses (bullous pemphigoid, pemphigus, epidermolysis bullosa, dermatitis herpetiformis), vesicular dermatoses (herpes simplex und zoster) as well as hereditary dermatoses (psoriasis, atopic dermatitis, dyskeratosis follicularis). The CEA levels were all within the range of healthy control persons (10.3-42.1 ng/ml). Our patients do not support the suggestion that certain dermatoses cause an increased production of CEA-like substances.

Experimental Differentiation between Phototaxis and Motility in Chlamydomonas snowiae

A reversible inhibition of phototaxis by acetic acid is demonstrated in Chlamydomonas snowiae. The inhibition is dependent on the pH of the medium and on the concentration of the inhibitor and does not act by affecting motility. Some substances closely related to fatty acids are also shown to be inhibitors of phototaxis, while certain metabolites have no effect. The possible mechanism by which the phototactic response is prevented is discussed.